1. Field of the Invention
This invention relates to a solid preparation coated with a continuous film coating layer having two or more different colors or a pattern of two or more different colors wherein the preparation is obtained by, in the common film coating of tablets, irradiating a part of the film coating layer containing one or more colorants with light, a process for the preparation of such solid preparations, and a film coating agent therefor.
2. Description of the Related Art
There are various forms of solid preparations such as tablets, granules, powders and capsules, and they vary widely in size and shape. Among others, tablets and capsules are typical solid preparations which have been used for long. Tablets are popular because of excellent mass productivity, easy ingestibility and handy shape. Capsules are a dosage form which has no unpleasant taste, can be easily ingested, and hence gains the favor of most people. In some cases, pharmaceutical makers put capsules on the market in spite of the fact that the same medicines can be manufactured in the form of tablets.
Solid preparations referred to generically as capsules include hard capsules and soft capsules. The former is formed of gelatin or the like, and consists of a body and a cap. They can be fitted together to contain a medicine and the like therewithin. For purposes of identification, the body and the cap are often formed so as to have different colors. The latter is a dosage form in which a medicine is enveloped with a film formed by adding glycerol or sorbitol to a capsule base (e.g., gelatin) and thereby increasing its plasticity. Soft capsules are classified into capsules formed by sandwiching a medicine between two films and fusing these films together, and seamless capsules formed by dropping solutions or suspensions into a hardening solution through a two-fluid nozzle (see the Pharmacopoeia of Japan, 13th Revised Edition, A-71). Generally, the brief term “capsules” refers to hard capsules in many cases. Also in the present invention, the brief term “capsules” refers to hard capsules.
Generally, capsules are a dosage form gaining the favor of consumers. However, in the early 1980s, an affair in which several persons were killed by a poison added to capsules happened in U.S.A. Since then, consumers' consciousness of safety was raised and the tendency to avoid capsules liable to the addition of a poison has increased. As examples of countermeasures against the addition of a poison, a method of labeling the joint of a capsule with a seal which is broken upon unsealing (U.S. Pat. No. 4,478,658) and a method of using a specially designed packaging material have been proposed. However, all of these countermeasures require an increased cost and, none the less, cannot entirely prevent the addition of a poison.
As a conclusive measure to prevent the addition of a poison, many pharmaceutical makers chose tablets to which a poison in powder form cannot be easily added. Among others, caplets having a long major diameter and hence a shape similar to that of capsules, and film-coated caplets, have found wide acceptance.
In the case of tablets, water-soluble film coating is widely employed for the purpose of masking an unpleasant taste of a drug, stabilizing a drug unstable to light by shielding from light, providing a color coating in order to enhance the identifiability of tablets, or preventing damage to tablets during transportation. Among others, a method using an aqueous solution of hydroxypropyl methylcellulose (HPMC) is most widely employed.
In the early days (1950s) of the development of film coating, the polymerization degree (viscosity) of HPMC used as the base material was high, and organic solvents were used to dissolve it. Thereafter, in the 1970s, the viscosity of the base material was increasingly reduced, and a ventilated pan coater was developed. As a result, the film coating techniques have gradually passed into the use of an aqueous system.
The film-coated tablets thus obtained has a single color, and cannot assume a dual coloration like capsules. However, consumers have a strong demand for capsules. That is, the easy ingestibility of capsules constitutes a psychological factor, and the image of capsules being more efficacious is expected to produce a placebo effect (U.S. Pat. No. 4,820,524). Accordingly, there has been a strong need for the development of preparations having two or more colors like capsules.
With respect to capsule-like preparations, a method of filling caplets, together with an adhesive, into a capsule (U.S. Pat. No. 4,928,840), a method of filling caplets into a capsule in a similar manner and then fitting them together (U.S. Pat. No. 5,511,361), and a method of filling half of the caplets into a capsule and fitting them together (U.S. Pat. No. 5,464,631) have been proposed. Although a capsule-like dual coloration can be realized by these methods, they have the disadvantages that they include troublesome steps and that it is preferable to provide caplets with a film coating in advance and thereby enhance their adhesion to a capsule.
There has also been proposed another method for coating caplets in which caplets are sandwiched between two gelatin films according to the method for the production of soft capsules. Since the tablet surface is coated with gelatin, this method can give a smooth surface and hence excellent ingestibility. However, this method cannot be used to provide tablets with a dual coloration like hard capsules.
Separately from the above-described methods of filling caplets into a capsule, a process for providing caplets with a capsule-like dual coloration by dipping them in a gelatin solution according to the method for the production of capsules (U.S. Pat. No. 4,820,524). This process involves film-coating caplets in advance and dipping them separately in two gelatin solutions having different colors, and requires special equipment similar to the gelatin capsule production equipment. Although this process comprises complicated steps, the resulting caplets can realize a gelatin-coated smooth surface and a capsule-like dual coloration, and have hence achieved a great success in the OTC market.
In order to provide tablets with a dual coloration, there has been proposed a method for producing tablets by preparing two tableting powders having different colors and tableting them according to the method for the production of two-layer tablets (U.S. Pat. No. 5,089,270). However, since this method compresses tablets in their longitudinal direction, the resulting caplets tend to be cracked at the interface between two layers and hence have a problem with strength. Moreover, it is difficult to provide tablets with a coating for improving ingestibility.
In recent years, with an increase in the age of patients, many patients tend to receive treatment for plural diseases, leading to a rise in the number of patients who must take plural tablets prescribed for these diseases. Under such situations, distinguishability of the tablets has been regarded to be very important in order to prevent a mistake not only upon prescription but also upon use by patients.
It is usually said that tablets are desirably distinguished by color, shape or size. Film-coated tablets are, however, in a single color and cannot assume dual coloration like capsules. Hence, they are inferior in distinguishablity to capsules which can assume desirable dual coloration.
In the 1960s of U.S.A., with the spread of prescription of tablets and an increase in the number of tablets taken by one patient, accidents happened frequently owing to a mistake in prescription. Since then, distinguishability of tablets has been carried out widely by employment of color film coating or use of tablets having a shape other than a disk.
On the other hand, in the same period of Japan, carcinogenicity of food colorants became a problem so that many tablets became white, which has lasted up to now. Since patients prefer white, small and disk-shaped tablets, many commercially available tablets are prepared as such. Hence, tablets not only tend to be identified incorrectly at the prescription site but also cause difficulty in medication guidance. Accordingly, there is a strong demand for the improvement of distinguishability of tablets.
As means for improving the distinguishability of tablets, variation in color, shape or size is desired as described above. For example, proposed (U.S. Pat. No. 4,820,524) is a method of imparting caplets with two different colors like capsules by dipping them in a gelatin solution, thereby imparting them with two different colors in accordance with the preparation process of capsules. However, this process needs a special apparatus similar to that for the preparation of gelatin capsules, because caplets which have been film-coated in advance must be dipped twice, more specifically, in two gelatin solutions different in color. This preparation process is thus cumbersome.
It is the common practice to engrave tablets or print the surface of film-coated tablets for improving the distinguishability of film-coated tablets.
Engraved tablets can be easily prepared by conventional film coating, the tablets which have been tableted with a engraved punch in advance. The film-coated tablets thus obtained are in a single color and not always have high distinguishability, however, because the engraving must be recognized from the difference in the brightness between the engraved surface and the rest of the tablet surface. Particularly, engraved tablets which are same in color cannot be distinguished easily. Moreover, symbols or logotypes complicated in shape disturb smooth tableting, thereby markedly shortening the life of the punch so that those usable for engraving are limited. Discrimination by engraving or logotypes involves further many problems such as covering or breaking of the engraved portion by film coating operation or bridging of logotypes.
For identification by printing, tablets are film-coated in a conventional manner, followed by printing. In this case, numerals, engraving or logotypes are printed. However, an increase in the printed area needs long drying time. Another drawback of such identification is that the printed letters become indistinct by rubbing.
As well as engraving or printing, packaging can also be applied to the identification of tablets. In case a package is opened and plural medicaments therein are divided into sub-packages or in other cases, packaging is not effective for identification. Thus its effect is limited.
Use of tablets different in shape does not always bring about an improvement in identifiability, because tableting for smaller and more complex tablets including engraved tablets tends to cause troubles. In addition, the tablets cannot be increased in size freely.